Numerous types of flat plate collector panel assemblies have been devised for solar installations. In flat plate collectors, customarily an absorber plate is deployed which is suitably comprised of steel, aluminum or copper plate coated with a mat black paint and characterized by its ability to absorb radiant energy and convert it to heat. The absorber plate is covered by a cover pane in order to reduce the heat loss from the plate without a corresponding reduction in the heat input due to the selective transmittance of the sun's rays by the glass or glazing. A thermal fluid, such as water, is circulated as a conducting medium in thermal contact with the absorber plate to remove some of the heat absorbed by the plate and this is typically done through the utilization of spaced parallel tubes mounted on the rear side of the absorber plate. The fluid-circulating tubes are connected to a common supply header at one end of the plate and to a return header at another end for transferring the thermal fluid from the tubing into a suitable heat storage area.
An insulating layer is disposed beneath the absorber plate and additional insulating layers may be disposed in surrounding relation to the absorber plate. The entire collector is assembled within a frame or tray generally comprised of a flat bottom and metal or wooden outer side- and end panels.
The supply- and return headers of on-roof collectors normally exit sideward from the frame, i.e. protrude through the collector panels with the header axis parallel to the plane of the cover pane. Thus, juxtaposed on-roof collectors can be connected by means of connecting tubing disposed above the roof that connects the return header of the one collector to the supply of the neighboring collector.
With in-roof collectors this type of construction is not possible, since a U-shaped flashing is disposed between neighboring collectors to ensure that water from precipitation will not reach the roof construction. The bottom of the U-shaped flashing is substantially level with the bottom of the collectors. The connecting tubing must pass below the U-shaped flashing. Therefore, the supply- and return header of known in-roof collectors, such as the Velux® CLI collector, are located a bracket that protrudes downwardly from the bottom of the collector, so that the sidewardly directed header axis and any connecting tubing is disposed below the U-shaped flashing. However, the downwardly projecting brackets increase the overall height of the collector thus leading to an increased volume of the shipment packaging. Further, the downwardly protruding header brackets are vulnerable to damage during manufacturing, transport and mounting on a roof.
It is therefore proposed to provide a solar collector for in-roof mounting that is robust, easy to manufacture, to transport and to install.